From: Al Viro <viro@ZenIV.linux.org.uk>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Miklos Szeredi <mszeredi@redhat.com>,
overlayfs <linux-unionfs@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 14/39] ovl: stack file ops
Date: Tue, 12 Jun 2018 19:24:23 +0100 [thread overview]
Message-ID: <20180612182423.GA30522@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CAJfpegvUkcUw0GXxFesT6V2f27EXW7jkvBpvnG4XB49BPdvjjA@mail.gmail.com>
On Tue, Jun 12, 2018 at 11:24:39AM +0200, Miklos Szeredi wrote:
> > Note that anything that uses file_dentry() anywhere near ->open(),
> > ->read_iter() or ->write_iter() is an instant trouble with your scheme.
> > Such as
> > int nfs_open(struct inode *inode, struct file *filp)
> > {
> > struct nfs_open_context *ctx;
> >
> > ctx = alloc_nfs_open_context(file_dentry(filp), filp->f_mode, filp);
> > if (IS_ERR(ctx))
> > return PTR_ERR(ctx);
> > nfs_file_set_open_context(filp, ctx);
> > put_nfs_open_context(ctx);
> > nfs_fscache_open_file(inode, filp);
> > return 0;
> > }
> >
> > You do want to support NFS for lower layers, right?
>
> There's no change regarding how file_dentry() works. We've just
> pushed these weird files (f_path points to overlay, f_inode points to
> underlay) down into the guts of overlayfs and are not directly
> referenced from the file table anymore. That shouldn't make *any*
> difference from the lower fs's pov.
*owwww*
I'd managed to push that particular nest of horrors out of mind ;-/
Having dug out my notes from back then and grepped around... The real
mess is not even /proc/*/maps - it's /proc/*/map_files/* and yes, the
reasons for that kludge are still valid ;-/
Fuck. OK, so we want to get rid of ->f_path.dentry accesses and see
that they don't come back. Leaving them around due to "it won't come
anywhere near overlayfs" was a mistake of the same kind as leaving
d_add() in ->lookup() instances where we'd been certain that filesystem
would never get exported over NFS. Just as we'd got open-by-handle for
e.g. NFS, we'd got nothing to prevent ecryptfs as lower layer in
overlayfs...
I hate it, but... consider path_open() objections withdrawn for now.
Uses of ->vm_file (and rules for those) are too convoluted to untangle
at the moment. I still would love to get that straightened out, but
it's not this cycle fodder, more's the pity...
next prev parent reply other threads:[~2018-06-12 18:24 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-29 14:43 [PATCH 00/39] overlayfs: stack file operations Miklos Szeredi
2018-05-29 14:43 ` [PATCH 01/39] vfs: dedpue: return loff_t Miklos Szeredi
2018-06-04 8:43 ` Christoph Hellwig
2018-06-05 8:33 ` Miklos Szeredi
2018-06-06 15:09 ` Darrick J. Wong
2018-06-18 20:08 ` Miklos Szeredi
2018-05-29 14:43 ` [PATCH 02/39] vfs: dedupe: rationalize args Miklos Szeredi
2018-06-06 15:02 ` Darrick J. Wong
2018-05-29 14:43 ` [PATCH 03/39] vfs: dedupe: extract helper for a single dedup Miklos Szeredi
2018-05-29 15:41 ` Amir Goldstein
2018-05-29 16:04 ` Amir Goldstein
2018-06-04 8:44 ` Christoph Hellwig
2018-05-29 14:43 ` [PATCH 04/39] vfs: add path_open() Miklos Szeredi
2018-06-04 8:46 ` Christoph Hellwig
2018-06-10 4:36 ` Al Viro
2018-05-29 14:43 ` [PATCH 05/39] vfs: optionally don't account file in nr_files Miklos Szeredi
2018-06-04 8:47 ` Christoph Hellwig
2018-06-04 8:57 ` Miklos Szeredi
2018-06-10 4:41 ` Al Viro
2018-05-29 14:43 ` [PATCH 06/39] vfs: add f_op->pre_mmap() Miklos Szeredi
2018-06-04 8:48 ` Christoph Hellwig
2018-06-05 11:36 ` Miklos Szeredi
2018-05-29 14:43 ` [PATCH 07/39] vfs: export vfs_ioctl() to modules Miklos Szeredi
2018-06-04 8:49 ` Christoph Hellwig
2018-06-10 4:57 ` Al Viro
2018-06-11 7:19 ` Miklos Szeredi
2018-06-11 16:24 ` Christoph Hellwig
2018-06-19 14:04 ` Miklos Szeredi
2018-06-19 14:24 ` Christoph Hellwig
2018-06-19 14:34 ` Miklos Szeredi
2018-06-19 14:54 ` Al Viro
2018-05-29 14:43 ` [PATCH 08/39] vfs: export vfs_dedupe_file_range_one() " Miklos Szeredi
2018-05-29 14:43 ` [PATCH 09/39] ovl: copy up times Miklos Szeredi
2018-05-29 14:43 ` [PATCH 10/39] ovl: copy up inode flags Miklos Szeredi
2018-05-29 14:43 ` [PATCH 11/39] Revert "Revert "ovl: get_write_access() in truncate"" Miklos Szeredi
2018-05-29 14:43 ` [PATCH 12/39] ovl: copy up file size as well Miklos Szeredi
2018-05-29 14:43 ` [PATCH 13/39] ovl: deal with overlay files in ovl_d_real() Miklos Szeredi
2018-05-29 14:43 ` [PATCH 14/39] ovl: stack file ops Miklos Szeredi
2018-06-10 4:13 ` Al Viro
2018-06-11 7:09 ` Miklos Szeredi
2018-06-12 2:29 ` Al Viro
2018-06-12 2:40 ` Al Viro
2018-06-12 9:24 ` Miklos Szeredi
2018-06-12 18:24 ` Al Viro [this message]
2018-06-12 18:31 ` Al Viro
2018-06-13 9:21 ` Miklos Szeredi
2018-06-15 5:47 ` Al Viro
2018-06-18 11:50 ` Miklos Szeredi
2018-06-13 11:56 ` J. R. Okajima
2018-05-29 14:43 ` [PATCH 15/39] ovl: add helper to return real file Miklos Szeredi
2018-06-10 5:42 ` Al Viro
2018-06-11 8:11 ` Miklos Szeredi
2018-05-29 14:43 ` [PATCH 16/39] ovl: add ovl_read_iter() Miklos Szeredi
2018-05-29 14:43 ` [PATCH 17/39] ovl: add ovl_write_iter() Miklos Szeredi
2018-05-29 14:43 ` [PATCH 18/39] ovl: add ovl_fsync() Miklos Szeredi
2018-05-29 14:43 ` [PATCH 19/39] ovl: add ovl_mmap() Miklos Szeredi
2018-06-10 5:24 ` Al Viro
2018-06-11 7:58 ` Miklos Szeredi
2018-05-29 14:43 ` [PATCH 20/39] ovl: add ovl_fallocate() Miklos Szeredi
2018-05-29 14:43 ` [PATCH 21/39] ovl: add lsattr/chattr support Miklos Szeredi
2018-05-29 14:43 ` [PATCH 22/39] ovl: add ovl_fiemap() Miklos Szeredi
2018-05-29 14:43 ` [PATCH 23/39] ovl: add O_DIRECT support Miklos Szeredi
2018-06-10 5:31 ` Al Viro
2018-06-11 8:08 ` Miklos Szeredi
2018-05-29 14:43 ` [PATCH 24/39] ovl: add reflink/copyfile/dedup support Miklos Szeredi
2018-05-29 14:43 ` [PATCH 25/39] vfs: don't open real Miklos Szeredi
2018-05-29 14:43 ` [PATCH 26/39] ovl: copy-up on MAP_SHARED Miklos Szeredi
2018-05-29 14:43 ` [PATCH 27/39] ovl: obsolete "check_copy_up" module option Miklos Szeredi
2018-05-29 15:13 ` Amir Goldstein
2018-05-30 8:26 ` Miklos Szeredi
2018-05-29 14:43 ` [PATCH 28/39] ovl: fix documentation of non-standard behavior Miklos Szeredi
2018-05-29 14:43 ` [PATCH 29/39] vfs: simplify dentry_open() Miklos Szeredi
2018-05-29 14:43 ` [PATCH 30/39] Revert "ovl: fix may_write_real() for overlayfs directories" Miklos Szeredi
2018-05-29 14:43 ` [PATCH 31/39] Revert "ovl: don't allow writing ioctl on lower layer" Miklos Szeredi
2018-05-29 14:43 ` [PATCH 32/39] vfs: fix freeze protection in mnt_want_write_file() for overlayfs Miklos Szeredi
2018-06-04 8:50 ` Christoph Hellwig
2018-05-29 14:43 ` [PATCH 33/39] Revert "ovl: fix relatime for directories" Miklos Szeredi
2018-05-29 14:43 ` [PATCH 34/39] Revert "vfs: update ovl inode before relatime check" Miklos Szeredi
2018-05-29 14:43 ` [PATCH 35/39] Revert "vfs: add flags to d_real()" Miklos Szeredi
2018-05-29 14:43 ` [PATCH 36/39] Revert "vfs: do get_write_access() on upper layer of overlayfs" Miklos Szeredi
2018-05-29 14:43 ` [PATCH 37/39] Partially revert "locks: fix file locking on overlayfs" Miklos Szeredi
2018-05-29 14:43 ` [PATCH 38/39] Revert "fsnotify: support overlayfs" Miklos Szeredi
2018-05-29 14:43 ` [PATCH 39/39] vfs: remove open_flags from d_real() Miklos Szeredi
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